How do I copy a pose from one blend file and paste it to another?
With your armature selected look in the properties panel at the object data tab.

The first thing you see at the top of the tab is your Pose Library pannel

Create a library and add your pose to it.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Rigging/Posing/Pose_Library

save your blend.

in your new blend, you can append the pose library (from the Actions folder). 
You can then add the poses via the Action Editor